The present invention pertains to a composition and associated methods that are useful for chemical mechanical planarization (chemical mechanical polishing, CMP) and which afford high selectivity for removal of metal in relation to dielectric material during CMP processing of substrates comprised of metal and dielectric material.
Chemical mechanical planarization (chemical mechanical polishing, CMP) is now widely known to those skilled in the art and has been described in numerous patents and open literature publications. Some introductory references on CMP are as follows: “Polishing Surfaces for Integrated Circuits”, by B. L Mueller and J. S. Steckenrider, Chemtech, February, 1998, pages 38-46; and H. Landis et al., Thin Solids Films, 220 (1992), page 1.
In a typical CMP process, a substrate (e.g., a wafer) is placed in contact with a rotating polishing pad of a table-mounted polisher, which also has a rotating platen onto which the substrate is mounted. A (carrier) platen applies pressure against the backside of the substrate. During the polishing process, the pad and the platen of the table are rotated while a downward force is maintained against the substrate back. An abrasive and chemically reactive mixture, commonly referred to as a slurry, is applied to the pad during CMP processing. The slurry initiates the planarization (polishing) process by chemically reacting with the film being planarized. The CMP process is facilitated by the rotational movement of the pad relative to the substrate as slurry is being provided directly to the substrate/pad interface. Polishing is continued in this manner until the desired film on the substrate is removed with the usual objective being to effectively planarize the substrate (both metallic and dielectric portions).
CMP processing is often employed in semiconductor manufacturing to remove excess metal at different stages. For example, in one semiconductor manufacturing process, metallized vias or contacts are formed by a blanket metal deposition followed by a chemical mechanical planarization (CMP) step. In a typical process, via holes are etched through an interlevel dielectric (ILD) to interconnection lines or to a semiconductor substrate. Next, a thin adhesion layer such as tantalum nitride and/or tantalum is often formed over the ILD and is directed into the etched via hole. Then, a metal film is blanket deposited over the adhesion layer and into the via hole. Deposition is continued until the via hole is filled with the blanket deposited metal. Finally, the excess metal is removed by CMP processing to form metal vias that have been planarized.
Typically metal CMP slurries contain an abrasive material, such as silica or alumina, suspended in an oxidizing, aqueous medium. In metal CMP processing, it is usually important that the removal rate of metal be significantly higher than the removal rate for dielectric material in order to avoid or minimize defects (such as dishing or erosion).
The use of silicone resin particles as fillers in polymeric films to tailor properties of the films is disclosed in various patent references, such as U.S. Pat. No. 5,626,959; U.S. Pat. No. 5,614,313; U.S. Pat. No. 6,060,156; WO 99/33910; and US 2002/10009564. Inclusion of these resin particles in polymeric films can modify/tailor the properties of the film in desirable manners, such as lowering haze level; affording speckle-free films, etc.
A CMP composition containing silane-modified abrasive particles is disclosed in WO 01/04226 and is reported to afford reduction of oxide (dielectric) loss during CMP processing.
A cleaning and polishing agent composition containing phenyl-modified silicone is disclosed in JP 11080671 A and JP 2974988 B2 and is reported to be particularly useful in cleaning and polishing hard surfaces.
An abrasive suitable for polishing a layer of insulating film is disclosed in JP 09324174 A. This abrasive contains composite particles containing organic polymer and polysiloxane chemically bonded with at least one silicon atom of the polysiloxane being bonded with carbon of the polymer. The polysiloxane component contains at least 25 weight percent of silica. The disclosed compositions also can contain a dispersion medium of water and/or alcohol.
A polishing grit and chemomechanical polishing slurry are disclosed in JP2001240848 A. The polishing grit has a polysiloxane coating of a given abrasive particle and is used in a CMP slurry.
A polishing composition for metals is disclosed in JP 53063691 and contains as components alumina particles and silicone polymer.
An abrasive article having a bond system comprising a polysiloxane is disclosed in WO 96/33841 in which the article comprises abrasive particles and a bond system of a binder and a polysiloxane. The article is stated to possess good abrasive efficiency.
An abrasive composition suitable for use in manufacture of abrasive tools is disclosed in U.S. Pat. No. 3,525,600. The composition contains abrasive grains coated with a ceramic and a silicone resin.
Ethoxylated acetylenic glycols having low surface tension and which are suitable as surfactants in aqueous coating systems are disclosed in U.S. Pat. No. 5,650,543.
A polishing composition for use in polishing a hard disk substrate is disclosed in JP97168966A. This composition contains an abrasive and an acetylenic diol defoamer.
CMP slurries that optionally can contain various surfactants are disclosed in U.S. Pat. Nos. 6,309,560 B1; 6,063,306; and 5,527,423.
While the above compositions are useful in various respects, these compositions (and their associated methods) are not suitable for use in CMP of a substrate comprised of a metal and a dielectric material to afford a high selectivity for removal of metal in relation to dielectric during CMP processing. Having high selectivity for metal removal during metal CMP processing is important to prevent dishing and other processing defects. There is a need for compositions (and associated methods) that provide high selectivity for metal removal during CMP. The present invention provides a solution to this significant need.